Study On The Polymorphisms Of PGR And TTF-1Gene In Sheep

Exon4of the PGR gene, partial sequence of exon2of the TTF-1gene wereamplifed and subjected to Single Strand Conformational Polymorphism (SSCP) invarious sheep breeds including Tibetan Sheep, Tan Sheep, Mongolian Sheep, SmallTail Han, German Merino, Texel and Poll Dorset. The relative expression of TTF-1mRNA in different tissues of sheep was detected by real-time quantitative PCRtechnique (SYBR Green Ⅰ method). All these studies provided basic date andreference for sheep molecular marker technology. The results shown as follows:1. The results of PCR-SSCP about the exon4of PGR gene indicated that thepolymorphic loci was controlled by a pair of alleles A and B, and there were3genotypes AA, BB and AB. Genotype AA was the dominant genotype and the alleleA was the dominant allele in all breeds. The polymorphism was not found in PollDorset and German Merino, and the heterozygosity was low in the detectedpolymorphic loci of PGR gene and the polymorphisms information content was lowpolymorphism (PIC<0.25) in the other five breeds. All breeds were atHardy-Weinberg equilibrium (P>0.05). χ2independence test results indicated thatthere was a extremely significant difference on genotype distribution between PollDorset and Tibetan Sheep (P<0.01), and a significant difference between Poll Dorsetand Mongolian Sheep (or Tan Sheep), German Merino and Tan Sheep (or TibetanSheep)(P<0.05). Sequence comparison revealed that the polymorphism was due tobase mutation of C to T at227bp (GenBank accession: Z66555.1520bp), but didn’tlead to amino acids change, so this was a synonymous mutation.2. The results of PCR-SSCP about the TS1primer of TTF-1gene indicated thatthe polymorphic loci was controlled by three alleles A, B and C, and there were3genotypes AA, AB and AC. Genotype AA was the dominant genotype. Sequencecomparison revealed that there were two base mutation of G to C and G to T at exon2(GenBank accession: FJ177515.2)173bp and176bp, respectively. Thepolymorphism in TTF-1-TS1amplified region was only found in Small Tail Han, Mongolian Sheep and Tibetan Sheep, and the heterozygosity was low, and in lowpolymorphism (PIC<0.25). All breeds were also at Hardy-Weinberg equilibrium(P>0.05). χ~2independence test results indicated that the genotype distribution wasdifferent between Small Tail Han and Texel (or Tibetan Sheep)(P<0.05).3. The results of mRNA expression level shown that TTF-1gene expressed inbrain, hypothalamus, pituitary, thyroid gland and ovary which associated withpubertal development and reproductive performance, and the expression level inthyroid gland was the highest, but the expression level was not significant differenceamong these tissues (P>0.05).